XPilot5 - Editors - XPKbConfig

It is all drag and drop.
In the above picture, i am dragging Toggle Mini from the X key, to the space bar.

To reassign a command, drag it from its current key, to the key you want it assigned to.

The Unused button/key contains the commands that are not assigned to your keyboard.

To delete a command, drag it to the Unused key.

To copy a command (have it bound to multiple keys), drag it to the Copy button.
The command will be left in it's original location,
and a copy will be placed on the Copy button. Then drag the copy to the key that you want.

The program supports multiple keyboard layouts.
The US Generic KB is built-in.
Other keyboards can be found in the (XPilotRoot)/lib/kbconfig directory.
The spec for keyboard layouts is here.